Lift truck



C. D. GIBSON May 7, 1968 LIFT TRUCK 4 Sheets-Sheet 1 Filed Jan. 1967CHRISTIAN D. GIBSON INVENTOR y 7, 1968 c. D. GIBSON 3,381,834

LIFT TRUCK Filed Jan. 4, 1967 4 Sheets-Sheet f5 CHRISTIAN D. GIBSONINVENTOR.

y 1968 c. D. GIBSON 3,381,834

LIFT TRUCK Filed Jan. 4, 1967 4 Sheets-Sheet 3 CHRISTIAN D. GIBSONINVENTOR.

C. D. GIBSON LIFT TRUCK May 7, 1968 4 Sheets-Sheet 4 Filed Jan. -i,196'? FIG. 3e

FIG. 3h

FlG 3d CHRISTIAN D. GIBSON ZM/im/ United States Patent ABSTRACT OF THEDISCLOSURE A detachable comb-line attachment carried on the front armsof a lift truck for stripping soft loads carried on sheets off of theforks of the truck.

This invention relates to material handling machinery, and moreparticularly, to an attachment which may be added to a lift truck to aidin the handling of certain types of loads.

In most warehouses, loads are carried on wooden pallets designed to behandled by lift trucks having two tines, or as they are frequentlytermed, two forks. Rail shipment of various commodities, such as paperbags of flour or sugar, for example, may be done more economically ifthe bags are not shipped on wooden pallets but instead carried oncardboard sheets (sometimes called slip sheets) or the like. Becausesoft, non-rigid loads of that nature, if not palletized, would fallbetween the forks of an ordinary two-fork truck, such loads must behandled with special fork arrangements which offer more supportingsurface area to the load. One satisfactory such fork arrangementinvolves the use of six forks spaced across the distance ordinarilyoccupied by two forks. While merely increasing the fork load-supportingsurface area readily adapts a truck for carrying such unpalletizedloads, it alone does not solve the problemof loading such loads onto theforks or the problem of removing such loads from the forks. In order topick up such loads, means must be provided to tilt the forks downwardly,to press the fork tips against the floor, so that the forks, which aretapered, will chisel under the cardboard sheet as the forks areadvanced. In order that the forks not merely push the load across thefloor as they are urged under the cardboard sheet, it is necessary, ofcourse, that the load be backed-up.

When a conventional palletized load is to be unloaded, merely loweringthe forks to the proper elevation completely frees the forks from thepallet, so that the forks need not touch the pallet or the load as theforks are retracted from the pallet. When a slip-sheet mounted load isto be unloaded, however, the weight of the load and the increasedload-supporting fork surface area provide a very substantial frictionwhich, it will be seen, will interfere with retraction of the forks frombeneath the load. Such loads have tended to stick to the forks as theforks have been retracted, preventing proper load placement, andsometimes damaging a load. Because handling of palletized loads is somuch more convenient, it is usually desired that such loads be placed ona pallet as soon as they are unloaded from a railroad car, andthereafter handled on the pallet.

In accordance with the present invention a truck of the above describedtype is provided with a comb-like attachment through which the loadforks may be retracted, with the teeth of the comb functioning to stripor comb the load from the forks to leave the load on a pallet. Inpractice, the base frame of the truck and comb are held fixed adjacentthe pallet upon which the load is to be placed, and the forks are thenretracted, preferably by use of a reach mechanism (such as the typeshown in US. Pat. No.

2,752,058 or US. Pat. No. 3,082,894, for example), but alternatively bytranslation of the entire mast assembly with respect to the base of thetruck in some trucks.

FIG. 1 is a perspective view of a lift truck equipped with sixclosely-spaced tines in its fork assembly to permit slip-sheet handling,with one form of a load stripper of the present invention shown mountedacross the forwardly-extending base legs of the truck.

FIG. 1a is an enlarged perspective view of a cutaway front end portionof the truck of FIG. 1, illustrating the relationship between the loadforks and the comb assembly of the present invention.

FIGS. 2a, 2b, and 2c are plan, elevation and side views, respectively,showing the load stripper mounted on the base legs of a truck.

FIGS. 3a-3h are schematic views illustrating the various operationsinvolved as a truck of the type described removes an unpalletized loadfrom one location, transports it to a second location and then unloadsit onto a standard wooden pallet.

FIG. 1 shows the general arrangement of one embodiment of the inventionincorporated on a lift truck equipped for slip-sheet load handling. Thetruck comprises a base frame carried on one or more dirigible, powereddrive wheels 12, only one of which is shown in FIG. 1, and a pair ofnon-steerable load-carrying front wheel assemblies 14 and 15 mounted onforwardlyextending straddle arms 16 and 17 which project forwardly fromthe base of the truck. An operators platform, various control apparatus,and the truck electrical storage battery (mounted Within compartment 18)are all carried on the main base frame of the truck, together with amast or gallows formed by a pair of inwardly-facing channel members 19and 20. A pair of telescopic uprights shown as comprising I-shapes 21and 22 are nested within channels 19 and 20 and are raised and loweredby hydraulic cylinder 23. A rectangular frame or load carriage 24 iscarried on rollers (not shown) within the tracks formed by the flangesof I-shapes 21, 22, and hydraulic cylinders 25 and 26 serve to raise andlower carriage 24 with respect to telescopic I-shape uprights 21, 22.Carried on load carriage 24 and attached thereto by means of anextensible and retractable scissors reach mechanism is fork carriageassembly 26. The reach mechanism preferably comprises an arrangement ofthe type disclosed in my prior Pat. No. 3,082,894. Fork carriageassembly 26 carries a plurality of tines of forks 31 through 36 whichare spaced laterally across the fork carriage. Fork carriage assembly 26also carries mechanism which allows all of the forks 31-36 to be tiltedupwardly and downwardly, 4 degrees from the horizontal in each directionbeing the maximum amount of tilt provided in one embodiment of theinvention. The utility of the truck in FIG. 1 may be considerablyincreased if it can be used for normal palletized load handling with atwo-tine fork as well as slipsheet load handling. Toward that end it ishighly desirable that at least four of the tines or forks be easily andrapidly removable and replaceable, and accordingly, the truckadvantageously may include a fork carriage assembly of the type shown incopending appl. Ser. No. 607,315, filed on even date herewith byStanford B. Jones and myself.

Shown in FIG. 1 extending between and connected to straddle arms 16 and17 is a comb assembly 37 having a plurality of fingers 38, 39 and 40 inthe form of plates spaced laterally inbetween various pairs of theforks, with the front faces of plates 38-40 parallel with the forwardends of arms 16, 17. The details of comb assembly 37 are shown in FIGS.la and 2a2c, to which reference now may be had.

In the exemplary embodiment of the invention shown in FIGS. la and2a-2c, the vertically extending fingers 38-40 comprise upward extensionsof a front plate 41 which extends entirely across the space between arms16 and 17, and which is mounted flush with the forward faces 16a and 17aof arms 16 and 17. It is essential that at least two vertical fingersextend upwardly sufficiently to extend above the top of a standard-sizepallet lying on the floor, and in one successful embodiment of theinvention they extended approximately ten inches above the floor. Thefingers may extend upwardly much higher, however, just so that they donot interfere with lowering of the fork carriage to a level where thefork tips may touch the floor when tilted maximum downwardly. It will beunderstood that comb assembly 37, in extending between the two arms 16and 17 extends perpendicular to the direction of extension andretraction of the reach mechanism of the truck. Also it will beappreciated that if a truck equipped with the assembly 37 is driven upto an empty pallet on the floor to a point where one or more fingers38-40 engages the side of the pallet, that the assembly provides a flatsurface which will rotate the empty pallet if necessary to correctlyalign it with the direction of travel of the truck reach mechanism. Thecomb assembly also includes a plurality of braces 44, 45 (7 are shown)which interconnect front plate 41 and rear plate 43. Braces 44, 44support finger members 38-40.

It is desirable that the comb assembly be easily removable andreplaceable in order that the truck be readily converted between pallethandling and sheet handling modes, and toward that end comb assembly 37is arranged to hook onto the front of arms 16 and 17 and to be held inplace by merely two bolts 47, 47. Each straddle arm is shown in FIG.242-20 as having a pair 14, 15 of load rollers or wheels mounted nearits front end in a pair of recesses within the assembly. The frontrecess in each arm is provided with an upper lip or edge 50 (see FIG.20) adapted to be engaged by a hook portion (52 or 53) attached at eachend of cross-piece 41. While the embodiment of the invention disclosedherein includes three fingers (38-46), it should be apparent that as fewas two fingers would be sufficient in some embodiments of the invention,and that more than three fingers might be preferred in others.

The sequence of operation of the truck will be clear from the successiveviews of FIG. 3, to which reference now may be had.

In FIG. 3a the truck is shown positioned adjacent a load of smallpackages carried on a cardboard sheet. The reach mechanism has beenfully extended and the fork tilt mechanism tilted maximum downwardly,and the carriage lowered so that the fork tips all press tightly againstthe floor. The operator then drives the truck forward, slowly until allfork tips are under the load, and then more rapidly in one continuousmotion, to chisel the forks all the way under the cardboard sheet, asshown in FIG. 3b. Next, the forks are tilted partly upward, the carriageelevated slightly, and the truck backed slowly for a short distance toseparate the load from any adjacent loads or walls, and then the forksare tilted maximum upwardly (typically four degrees from horizontal) tocradle the load within the forks, and FIG. 3c illustrates the truckafter such operations have been performed. The carriage is then elevatedhigh enough for the tops of the fork (i.e. the bottom of the cardboardsheet) to clear the tops of the comb members of the load stripper andthen the reach mechanism is retracted, as shown in FIG. 3d. The truck isthen ready to be driven out of the boxcar or other site to the warehousedock or other location where the load is to be unloaded onto a pallet.

In FIG. 3c the truck has been driven up to a pallet, to a point wherethe front faces of the comb members of the load stripper aresubstantially contiguous to the side of the pallet. The reach mechanismis then. extended until the back of the load is beyond the front facesof the comb members, and then the load carriage is lowered until theforks are only a few inches above the pallet, as shown in FIG. 3f. Theforks are then tilted downwardly (and the carriage again lowered, ifnecessary) until the forward (outward) of the load is resting on thepallet. The forks are then withdrawn by retracting the reach mechanism.FIG. 3g shows the truck just beginning to retract the forks. Even thoughthere may be considerable friction between the forks, the pallet and theload, the vertical comb members of the load stripper will hold both thepallet and the load stationary and in place while the forks slide outfrom between them. While most lift truck reach mechanisms do not extendand retract far enough to completely withdraw the forks from between thepallet and the cardboard sheet, enough of the weight of load will reston the pallet when the forks are perhaps half-withdrawn (FIG. 3/2) thatneither the load nor the pallet will move if the truck is then backed tocompletely withdraw the tips of the forks from under the load.

As mentioned above, the invention is applicable as well to lift trucksprovided with traveling masts in lieu of scissors reach mechanisms, andbecause adaptation of the invention to such a truck should now beobvious as a result of this disclosure, no detailed description of suchalternative arrangement is deemed necessary.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained, andsince certain changes may be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained or shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. In a material handling vehicle comprisin a base with a pair offorwardly-extending arms each having a wheel assembly near its outerend, a fork carriage carrying a plurality of forwardly-facing generallyL-shaped load forks spaced at intervals across said fork carriage, meansfor translating said fork carriage relative to said base in generally upand down vertical directions and forward and rearward directions, andmeans for tilting said load forks to raise and lower the tips thereof,the combination of a comb member mounted between said arms, said combmember having a plurality of fingers laterally spaced between said loadforks and extending vertically from an elevation below the top of astandard height pallet up more than the maximum downward tilt distanceof said tips of said load forks.

2. Apparatus according to claim 1 in which said fingers comprise platesthe forward faces of which are coterminous with the forward ends of saidarm members.

3. Apparatus according to claim 1 in which said L- shaped load forksinclude generally horizontal lower portions to collectively provide agenerally horizontal loadsupporting surface area and generally verticalback portions to provide a generally vertical load-supporting surfacearea, and in which said fingers comprise plates, the forward faces ofwhich are located slightly rearwardly of said vertical load-supportingsurface area with said fork carriage translated to its forwardmostposition.

References Cited UNITED STATES PATENTS ALBERT J. MAKAY, PrimaryExaminer.

